@data = <DATA>;

@extracted = ();
foreach(@data){
   while ($_ =~ s/(foo\d+)//) {
    push @extracted, $1;
  }
}

print join( ':', @extracted ), "\n" ;

__DATA__
foo1 foo2 foo3
foo4 foo5 foo6
foo7 foo8 foo9

##</code><code>##

@data = <DATA>;

my @extracted = grep { /foo\d+/ } map { split } @data ;

print join( ':', @extracted ), "\n" ;

__DATA__
foo1 foo2 foo3
foo4 foo5 zoot6 foo6
foo7 foo8 bar1 foo9